Radar stands for Radio Detection and Ranging. Radar systems typically transmit a pulsed electromagnetic wave, which is scattered or reflected by objects, particles and/or irregularities in the refractive index of the atmosphere. The radar system can utilize the reflected waves to determine the characteristics of objects, particles, and/or atmospheric phenomena that are responsible for the reflections. A high gain antenna is typically utilized to focus the transmission. Ranging can be performed based upon the time delay between the transmitted and received signals. The range resolution is typically determined based upon the frequency bandwidth of the transmitted electromagnetic pulse. Angular resolution is impacted by the beam width of the transmitted signal.
The sensitivity of a radar system increases as the frequency of the transmitted electromagnetic pulse increases if all other parameters are kept constant. However, atmospheric absorption and attenuation of radar transmission generally increases with increased frequency. Many high resolution radar systems utilized in atmospheric research transmit within the Ka band. The Ka band is typically defined to cover frequencies of 26.5-40 GHz (i.e. wavelengths from slightly over one centimeter down to 7.5 millimeters).
Many radars that operate in the Ka band utilize a digital to analog converter to synthesize an electromagnetic pulse that is modulated to an intermediate frequency, where it is filtered to remove an image signal. The filtered intermediate frequency signal is then modulated to a carrier frequency for transmission. A similar process can be used in reverse during demodulation of reflected transmissions.